1. Field of the Invention
The present invention relates to electronic apparatus for vehicle, a method for optimally correcting a sound field in a vehicle, and a sound field optimum correction system in a vehicle, and is applicable to a head unit of vehicle audio to be attached to a center console panel at the almost center between the driver's seat and the passenger seat in a vehicle, for example.
2. Description of the Related Art
Heretofore, in a vehicle audio system, even if audio reproducing is performed in a vehicle, a listening point is not at the center between a left speaker and a right speaker, and is shifted to either of the driver's seat or the passenger seat.
Thus, in such listening point, distances from each speaker to the above listening point are respectively different, so that also the frequency characteristics of sounds from each speaker and those of sounds at each listening point are respectively different. Therefore, it has been in a situation that it is hard to say a user listens to audio at the optimum listening position.
To solve this, a sound field correcting apparatus in which correction information on at least two normal correcting positions is obtained, and correction information on a correcting position other than the normal correcting positions is obtained by operation using that information has been proposed (see Japanese Patent Laid-Open No. 2005-341384, for example).
Further, in a vehicle audio system, audio signal waves are reflected in a vehicle owing to the form of the vehicle space. The audio signal waves and the reflected waves interfere with each other, so that standing waves are generated. Therefore, the frequency characteristic is apt to be disturbed.
To improve such listening environment, “vehicle audio system adjustable by equalizer” and “vehicle audio system capable of time alignment adjustment” in that a measurement microphone is installed at a listening point, a sound reaching time from each speaker installed in a vehicle is measured, and the output timings of sounds by each speaker are controlled, so that the phase of a sound wave from each speaker is adjusted properly, and the disturbance of the frequency characteristic of the each sound wave by interference is restrained has been developed.
With respect to such equalizer adjustment and time alignment adjustment, there are two ways of the case where it is manually performed based on sound field data measured in a vehicle relying on the sense of hearing of people, and the case where a vehicle audio system itself automatically performs processing from sound field measurement to reflecting the result.